From the expression of glee on Sherlock's face, John knew this wasn't going to be a pretty crime scene. He planned accordingly, taking several motion sickness tablets as soon as they hopped out of the cab and into the crisp, blinding light of a Highland sunset.

"This is a funny one," the rough Glaswegian accent of George MacKenzie, the commanding officer, intoned gruffly, and Sherlock smiled seemingly to himself. "Found this body at the bottom of the loch; got caught up in a deep fishing net. Looks like it drifted toward the edge of the loch from more of the middle. And it's covered in this stuff – maybe the killer encased it in wax?"

Sherlock ignored the man's words and knelt down next to the body, which had been turned a disturbing green not unlike a piece of oxidized copper. Snapping on his latex gloves, his ran his finger along the edge of the corpse's arm and then rubbed his index and thumb together. John and the officer merely watched as the detective delicately leaned forward to sniff at the waxen face.

"Do you have any candle shops around here? Lots of the larger candle manufacturers have huge vats of hot wax. Maybe they tipped the victim into one of these vats, waited for them to harden, and then cut the corpse out and dumped it in the loch?" John suggested. Sherlock continued to ignore both of them, so the doctor turned back to MacKenzie. "Candle-making, I mean the old ways of it, are dying out and being replaced by huge mechanized business, big conglomerates. Maybe this person was a rival candlemaker and so the killer wanted them out of the way. Business can get rough when you're in a declining industry. Sherlock?"

The man in question stood up, his catlike face alight with joy. "Admirable deduction, John. I'm very impressed with how you're learning."

John bit his lip to keep from beaming.

"But you're horribly wrong. Just absolutely off the mark." He waved his hand toward the wet corpse with a grand flourish. "This man – in his 40's, likely from the Lowlands, here on holiday – died of cardiac arrest while they were in a rented dinghy. He was married – obviously, look at his finger – but they were having marital problems, which is why they chose to take this trip in the first place. He tipped off the side of the boat while in cardiac distress.

"His wife was a slight woman and couldn't fish him out. Everyone knew they were having troubles, so obviously suspicion would first fall on his wife; she panicked, took the dinghy back to the dock and immediately checked out of the hotel, saying that her husband was waiting for her in the car. No one noticed, being as they were holidaymakers and this is a sleeping town, and hence no missing persons report until far later, when she was already back at home. You're looking at the body of Alex Johnstone, from Peebles, who was reported missing five months ago." He held out his phone triumphantly, having pulled up the news story.

"But what about the waxy stuff?" John asked, clearly perplexed. Sherlock rolled his eyes.

"It's called adipocere, a substance formed by anaerobic bacterial hydrolysis of the body fat in a corpse. Happens occasionally when a body is subjected to low oxygen and pressure, such as in the mud at the bottom of a lake. That was my first clue that the body was left here originally. Doesn't look enough like candle wax to demonstrate your theory, and after that it was merely a matter of determining identity. The clothes are work wear, less than a year old and have the tag from a tailor in Peebles – barely legible but still there if you just carefully pull on the side of the shirt, which tells me that he lives around there: no one gets their clothes tailored on holiday, which eliminated the idea that they were doing a Scottish grand tour. Easy enough to look for missing persons from Peebles within the last year. Done and done."

"Marvelous!" John interjected. Sherlock smiled.

"You can write this one up as The Adventure of the Wax Man."